1. Field of the Invention
The present invention relates to the control of vehicles, in particular to the coordinated control of a number of subsystems of a vehicle.
2. Background Art
Various systems are known in which operation of various subsystems of a vehicle can operate in different configuration modes so as to suit different conditions. For example, automatic transmissions can be controlled in sport, winter, economy and manual configuration modes in which the changes between gear ratios and other subsystem control parameters are modified so as to suit the prevailing conditions or the taste of the driver. Air suspensions are known with on-road and off-road configuration modes. Stability control systems can be operated at reduced activity so as to give the driver more direct control over the operation of the vehicle. Power steering systems can be operated in different configurations modes where the level of assistance is at different levels or varies in different ways. Vehicle transmissions can be switched to provide drive to different numbers of wheels. Also the locking or partial locking of differentials can be controlled to suit the prevailing driving conditions.
As the number of controllable systems increases, the driver will become faced with an increasing number of choices as to which configuration modes to select for each of the systems. Unless the driver is very experienced, this can become complicated and confusing.
Therefore, systems have been proposed in which the control of a number of the vehicle subsystems is coordinated by a central vehicle controller, which can be switched between a number of modes thereby controlling all of the subsystems in a coordinated way which is simple for the driver to control. Such a system is disclosed in GB2273580.
While GB2273580 teaches an integrated control system to control and configure vehicle operating subsystems in response to control signals, drivers often encounter a broad range of surfaces and terrains in both on-road and off-road settings. Unfortunately, the operating characteristics of such an integrated control system does not provide the driver with the ability to provide direct input regarding the surface terrain in an attempt to better select the appropriate subsystem configuration modes. This deficiency results in the less than optimal stability, handling, and safety performance of the vehicle. Therefore, to further expand the performance of motor vehicles including integrated control systems as noted above, there is a need for an integrated control system which will provide improved control of the vehicle on a broad range of surfaces.